Petrogenetic Significance of Initial 87Sr/86Sr Ratios in the North Atlantic Tertiary Igneous Province in the Light of Rb-Sr, K-Ar and 18O-abundance Studies of the Sarqata qaqa Intrusive Complex Ubekendt Ejland, West Greenland

Abstract

A single Rb-Sr whole rock ‘isochron’ from three gabbroic and six granitic samples from the Sarqâta qáqâ Complex, Ubekendt Ejland, yields an age and initial ⁸⁷Sr/⁸⁶Sr ratio of 65±5 m.y. (λβ = 1.47×10^-11 yr^-1) and 0.7045±0.0003. K-Ar measurements on two biotite separates from the gabbro give ages of 55.4±1.5 and 54.0±1.5 m.y. Determinations of ¹⁶O/¹⁸O ratios in two gabbro and four granite samples yield average δ values of ±5.53±0.04 and +6.74± 0.37% respectively, relative to SMOW.